The invention relates to a clamping device for a tool or a workpiece, comprising at least one chuck and at least one holder for the workpiece or the tool.
Clamping devices of this generic type are used to clamp workpieces or tools, very high precision being demanded in the machining of the workpiece. In addition, an exactly reproducible clamping of the workpiece or the tool in the x, y and z directions must be ensured.
From EP-A-255 042, a clamping device is described wherein, for the accurate positioning of the two coupling members (chuck and holder) relative to one another in the z direction, which usually coincides with the clamping direction, a plurality of uprights are present on one of the clamping members and the z reference surfaces are configured on the free end faces of said uprights. On the other coupling member there are, in an arrangement corresponding to the uprights, a plurality of z counter reference surfaces, which lie in a common plane and, when the coupling members are clamped together, cooperate with the z reference surfaces. A similar arrangement for the z positioning of two coupling members is known from German registered utility model DE-U-295 21 030.
Another clamping device comprising two coupling members and a clamping mechanism is disclosed in EP 1 013 375 A2. A coupling device is described, consisting of a first coupling member and a second coupling member, as well as a clamping mechanism for the axial clamping together of the two coupling members, wherein projecting from the first coupling member are at least three prism pins, each of which is provided on at least one side with a prismatic surface, and wherein on the first coupling member there are configured at least three mutually spaced z reference surfaces, which lie in an x-y plane extending transversely to the clamping direction, and wherein, furthermore, the second coupling member has at least three grooves, which are aligned to the prism pins and on which axial-elastic elements for the accurate positioning of the coupling members relative to one another in the x-y plane are provided. In order to simplify the structural design of the z positioning of two coupling members, it is provided that the z reference surfaces are configured on the free end faces of the prism pins and a z counter reference surface is configured on the groove floor of each groove.
The problems and drawbacks associated with the current state of the art are described below.
The previous clamping devices can generally be used only for specific applications, so that a multiplicity of clamping devices are necessary to cover as wide a range of applications as possible. For the powder pressing process, for instance, high requirements are placed upon the tools and their clamping devices, in particular a high exposure to forces. It would further be advantageous if a clamping device could be used for different machining processes, for example in milling, in grinding, in EDM, or with other machine tools. Similarly, the clamping device should be usable for different tool forms (for instance, electrode forms in EDM), without time-consuming conversion times. One problem is to find a solution to clamping both the small-sized holders and the larger-sized holders to tools or workpieces on workpiece plates by means of a universally designed clamping device.
In addition, there is a requirement to provide in the coupling part designed for the clamping of a tool (drill, electrode, etc.) room to allow the tool to be firmly seated such that it can adequately withstand load. In high-speed milling cutters, specifically, this problem of the present state of the art is yet to be solved.
In addition, the drawback of undesirable lateral forces in the clamping phase often arises, caused by clamping balls or other clamping elements.
The object of the invention is thus to propose a clamping device which remedies these abovementioned drawbacks.